Republicans in 10 states will vote on Super Tuesday next week, and the general election battleground state of Ohio may be the most coveted prize.

NPR's Don Gonyea reports that both Mitt Romney and Rick Santorum are pushing hard for the state, where 63 delegates are at stake.

Santorum, the former senator from neighboring Pennsylvania, called Ohio "the center of the political universe in America," at a rally Friday in the southern Ohio city of Chillicothe. A Quinnipiac University poll on Friday showed Santorum's lead over Romney, the former Massachusetts governor, down to 4 percentage points in the state.

Ohio takes on renewed importance for Santorum because he failed to upset Romney in this week's Michigan primary. In the state where Romney was born and raised — and where Romney's father was a popular governor — Santorum came within about 3 percentage points of Romney by pulling together Tea Party voters, evangelicals and others who simply don't like Romney, Gonyea reports.

Ohio has similarities to Michigan demographically, but Romney can't count on a home state connection.

Another factor at play in Ohio is an active campaign of former House Speaker Newt Gingrich, who did not contest Michigan at all, but was scheduled to campaign in Ohio this weekend. Both Santorum and Gingrich are vying for the more conservative voters.

Santorum also is hurt by his own campaign's failure to meet requirements to get on the ballot in three of Ohio's 16 congressional districts, so he's not eligible to win nine potential delegates from those districts.

In Virginia, which votes Tuesday, Santorum failed to get on the ballot at all. So did Gingrich. Meaning that state — with 49 delegates — is open only to Romney and Texas Rep. Ron Paul. Polls show Romney winning Virginia easily.

While Santorum spent Friday in Ohio, Romney had a morning appearance in Washington state before traveling to Ohio. Washington holds its caucuses Saturday, and Paul campaigned there Friday.

Gingrich was in Georgia, his adopted home state, which has 76 delegates at stake, the most of any state voting on Tuesday.

NPR's Kathy Lohr reports that during a campaign swing in the Atlanta suburbs, Gingrich said of Romney and Santorum: "One's Massachusetts moderate baloney. The other is Pennsylvania big labor baloney. But they're baloney."

Polls show Gingrich leading in Georgia, and he acknowledged that a failure to win the state he represented in Congress for two decades could doom his presidential aspirations. "I have to win Georgia, I think, to be credible in the race," Gingrich said, Lohr reports. "But if I win Georgia, the following week we go to Alabama and Mississippi, I think I'll win both of those."